A simulation study of the distribution of β′ precipitates in a crept Mg-Gd-Zr alloy

H. Liu, W. F. Xu, L. M. Peng, W. J. Ding, J. F. Nie

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7 Citations (Scopus)

Abstract

A linear chain distribution of β′ precipitates is found in a Mg-2.4Gd-0.1Zr (at.%) alloy crept at 250 °C for 155 h or longer under a uniform tensile stress in a range of 80–120 MPa, which is distinctly different from the random distribution of β′ precipitates in the same alloy before creep tests. In this work, the influences of the applied stress and dislocations on the distribution of β′ precipitates and the formation of the linear precipitate chains are investigated via the interaction energy calculation and phase field simulation. Our calculation and simulation results indicate that the applied stress promotes the preferential growth of one of the three β′ variants during coarsening. The applied stress can also activate the gliding and climbing of dislocations during creep. Among these dislocations, the a-type basal edge dislocations are most likely to act as heterogeneous nucleation sites for β′ precipitates. Compared with the other two variants, the variant that has zig-zag monolayers of Gd atoms perpendicular to the dislocation line is more favourable to nucleate and grow along the dislocation line and form precipitate chains. This variant is also the one favoured by the applied stress.

Original languageEnglish
Pages (from-to)152-164
Number of pages13
JournalComputational Materials Science
Volume130
DOIs
Publication statusPublished - 1 Apr 2017

Keywords

  • Applied stress
  • Creep
  • Dislocation
  • Magnesium alloys
  • Phase field
  • Precipitate

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